Viewable Impression


In the online advertising industry, a Viewable Impression is a measure of whether a given advert was actually seen by a human being, as opposed to being out of view or served as the result of automated activity. The Viewable Impression guidelines are administered by the Media Rating Council and require that a minimum of 50% of the pixels in the advertisement were in an in-focus tab on the viewable space of the browser page for at least one continuous second.
The first system to deliver reports based on a Viewable Impression metric for standard IAB Display ad units, called RealVu, was developed by Rich Media Worldwide and accredited by the Media Rating Council on March 9, 2010. Other companies to offer viewable impressions include DMA-Institute OnScroll, C3 Metrics, Comscore, and AdYapper, while MSNBC utilizes ServeView, a proprietary system in use since 2010.
The definition of a Viewable Impression may depend on the type of the ad units and the reporting system. For example, a Viewable Impression for ads of pre-defined size delivered to pre-defined space on the content page is registered by RealVu when the Ad Content is loaded, rendered, and at least 60% of the ad surface area is within the visible area of a viewer's browser window on an in focus web page for at least one second. Click-through is enabled at the moment of the "viewable impression".
Viewable Impressions were developed as an improvement of the online impression metrics measured by first ad servers developed in the mid-1990s, which analyze HTTP requests in a server log and cannot provide information on events fired by a viewer’s browser; thus, they cannot measure whether ad content was actually visible to a viewer.

Overview

With the development of the first ad servers in 1995–1996 the assumption was that a requested ad was always available to the viewer of a requested web page. This allowed for the utilization of the server log file for collection of metadata to deliver a metric called the Online Impression that in traditional media meant an impression on a viewer.
This type of advertising metric was meant to resemble Television and print advertising methods for speculating the cost of an advertisement, with the promise of even more accuracy due to the interactive nature of the Internet eliminating the need for industry-accepted approximates such as Nielsen ratings for television and circulation figures for print publications.
The value of an ad traditionally was based upon an estimate of how many different people saw or heard the ad. The following are current accepted means of calculating CPM for different mediums:
With the advent of the Internet, through log file server collecting data it was believed that ad views could be tracked with unprecedented accuracy and “number of different prospects reached” was removed from the equation, and a new CPM equation was created for the internet:
However the assumption that an ad requested from an ad server is always visible when the viewer is on the requested page was wrong because of a few technical reasons and the fact that the web page is usually longer than the height of a computer screen. Eventually it became apparent that a large number of ad impressions measured for CPM pricing actually never rendered in the visible area of a viewer’s browser screen.

CPMV (Cost per Thousand Viewable ads)

Until 2010 it was very common for large publishers to charge for most of their advertising inventory on a CPM or CPT basis. A related term, effective cost per mille, is used to measure the effectiveness of advertising inventory sold via a CPC, CPA, or CPT basis.
Partially to avoid the limitations of server side impression methodology many models emerged that were based on direct response:
The Viewable Impression approach enables online advertising effectiveness to be analyzed based on stopping power, branding ability and level of engagement – the three key elements that drive purchase consideration and, ultimately, sales. Having no reliable way of measuring actual viewership, web publishers are vulnerable to payment methods that are based on performance-based advertising such as cost per click and cost per transaction. Since the publisher has no control or input on the demand and ad creative quality of the advertised product, web publishers lose control of their yield, giving away significant inventory to ads that are not clicked.
With the arrival of the Viewable Impression model – Cost per Thousand Viewable ads has emerged, quoted in terms of CPMV. This model may eventually become the standard CPM as it measured at the same point as television or print.

Architecture Example

Viewable Impression relies on Web bugs placed on the web pages or in the third-party ad servers that distribute ads on the website content pages. These tags are placed on a web page and when rendered, employing a "Correlator" The ad space is then "marked up," an "ad request” is recorded, and the Correlator begins communicating with the web page, browser and ad unit embedded in the webpage content. The Correlator can collect additional non-private information from the viewer’s browser, including the viewer’s operating system, browser type and version and a list of other ads that were previously rendered on the page to prevent duplication of ads on the content page. Once any portion of the ad unit, on a viewer's in focus web page, hits the visible area of the browser window a request is sent to an ad content server to deliver an advertisement.
Once the ad content is loaded and rendered an "Ad Rendered" is reported. The Correlator continues to monitor the ad space for each individual ad on the web page and its relation to the browser window dimensions, scrolling position and web page focus, considering if the viewer has scrolled the ad space in or out of the visible area of the browser window, minimized, tabbed away, or opened another browser or application window bringing the web page monitored out of focus or portion of the browser window with the ad space outside of the monitor screen. When 60%, of the ad content on a web page is within the visible area of the viewer's browser window for one second, a message is sent via Correlator and a "Viewable Impression" is reported. The Correlator code continues to monitor the web page focus and scrolling position, location of ad unit and the visible area of the browser window, and communicates to the reporting server logging the “Time in View” for the ads being delivered on the webpage.

Implementation

Reasons why an impression may not appear to a viewer overcome:
Reasons why an impression may not appear to a viewer associated with fraud overcome:
Limitations related to data analysis and distribution flow with impression methodology overcome: